A metal spraying gun as described in German published patent application Pat. No. 28 15 648.1 uses an electric heating system to produce a metal melt which system comprises a steel container having thin walls which are surrounded by a thick block of a thermally conductive metal such as an aluminum alloy. The block contains an electric heating element as well as a thermocouple and air channels. The molten metal is sprayed by using pressurized air. However the heating system is rather complicated and does not allow for quick heating operations. Another spraying gun as described in Swiss Pat. No. 603,250 comprises a container for molten metal having double walls between which the pressurized air is heated by a gas flame.
The gas burner is located underneath the container and forms a separate system which is fixed to the rest of the gun by simple screw connections. This device needs special care when used because the gas burner appears to be dangerous and the oxidizing action of the gas flame is in no way shielded from the metal to be sprayed.